Finding average data from a large data matrix
1 vue (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Matlab_G
le 18 Nov 2022
Commenté : Cris LaPierre
le 21 Nov 2022
Hello,
I have a data matrix in the following format:
Row 1 is the years from 1990 to 2000
Row 2 is the month
Row 3 is the day
Row 4 is the data
Ex:
1990 1990 1990 1990…..until 2000
1 1 1 1 1 1 1 1…2 2 2 2 2 2….3 3 3 3
1 2 3 4 5 6
How can I calculate the average data of each month (ie. all the jan, feb, together)? The problem that I am encountering is finding a systematic way of dividing the data, given its format.
Thanks in advance
0 commentaires
Réponse acceptée
Benjamin Thompson
le 18 Nov 2022
An index vector over the available columns would work well here. Cannot be sure without a complete example of the data. Then pass the index vector as the second subscript argument for the submatrix of A that you want to pass to the "mean" function to get the average.
>> A = [1990 1990 1991 1991 1992 2000; 1 2 3 4 1 2; 1 2 3 4 5 6; 1 2 3 4 5 6]
A =
1990 1990 1991 1991 1992 2000
1 2 3 4 1 2
1 2 3 4 5 6
1 2 3 4 5 6
>> I_feb = A(2,:) == 2
I_feb =
1×6 logical array
0 1 0 0 0 1
>> mean(A(4,I_feb))
ans =
4
2 commentaires
Benjamin Thompson
le 21 Nov 2022
The index vector can use a more complex logic test:
I_two_conditions = (A(1,:) == 2000) & (A(2,:) == 1)
Plus de réponses (2)
Cris LaPierre
le 18 Nov 2022
data = [1990 1990 1990 1990 1995 1995 1995 1995;
1 1 2 2 1 1 2 2;
1 2 1 2 1 2 1 2;
3 5 7 4 6 8 1 9]'
avgData = groupsummary(data(:,4),[data(:,1),data(:,2)],'mean')
This is probably easier to understand if you turn your data into a table.
dataT = array2table(data,'VariableNames',["Year","Month","Day","Data"])
avgDataT = groupsummary(dataT,["Year","Month"],"mean","Data")
One more may to do this is if you turn your date info into a datetime variable
dataT2 = table(datetime(data(:,1:3)),data(:,4),'VariableNames',["Date","Data"])
avgDataT2 = groupsummary(dataT2,"Date","month","mean","Data")
0 commentaires
dpb
le 18 Nov 2022
tData=array2table(X.','VariableNames',{'Year','Month','Day','Data'});
tMonthAvg=rowfun(@mean,tData,'GroupingVariables',{'Month'}, ...
'InputVariables','Data','OutputVariableNames','MonthAverage');
1 commentaire
Cris LaPierre
le 21 Nov 2022
A= [2000 2000 2000 2001 2001;
1 1 2 1 1;
5 3 8 9 7]'
groupsummary(A(:,3),[A(:,1) A(:,2)],'mean')
Voir également
Catégories
En savoir plus sur Matrices and Arrays dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!